Clean up ImeVisibilityApplier#perform{show, hide}Ime

To solve a ping-ponging between the computer state and the applier
that the ideal flow should as below to apply IME visiblity directly
rather than backing to computer to set another state (i.e. In applier,
setting show or hide input token to the computer):

(app window) -> Computer -> Applier -> (IME)

Fix: 246309664
Test: atest CtsInputMethodTestCases
Test: atest DefaultImeVisibilityApplierTest
Change-Id: I448bbb6770dcb8983ffd62979f64ced3b6c368d4